Injection molding machine and method of operating the same

Abstract

An injection molding machine has a clamp that generates electromagnetic force and that secures a moving plate or a fixed plate using attractive force that is produced by the electromagnetic force; and a controller that controls separation force that acts on the moving plate or the fixed plate such that the separation force is less than the attractive force.

What is claimed is: 
     
         1 . An injection molding machine comprising:
 a clamp that generates an electromagnetic force and that secures a moving plate or a fixed plate to the clamp using an attractive force that is produced by the electromagnetic force; and   a controller configured to control a separation force that acts on the moving plate or the fixed plate such that the separation force is less than the attractive force in a molding process from start of a first operation to release a closed-mold state to completion of a second operation to form a next-closed mold state.   
     
     
         2 . The injection molding machine according to  claim 1 , further comprising a clamping mechanism that drives the moving plate, wherein:
 the separation force is a mold-opening force that is generated in the moving plate or the fixed plate in a mold-opening step, and   the controller is configured to control the clamping mechanism such that the mold-opening force is less than the attractive force.   
     
     
         3 . The injection molding machine according to  claim 2 , wherein the controller is configured to control a mold-opening speed of the moving plate such that the mold-opening force is less than the attractive force. 
     
     
         4 . The injection molding machine according to  claim 3 , wherein:
 the moving plate has a sliding part that slides relative to the fixed plate and that thereby generates the mold-opening force, and   the controller is configured to control the mold-opening speed of the moving plate such that the mold-opening force is less than the attractive force after a main body of the moving plate is separated from the fixed plate and until the sliding part is separated from the fixed plate.   
     
     
         5 . The injection molding machine according to  claim 3 , further comprising:
 an input portion for three-dimensional shape data of the moving plate and the fixed plate; and   an estimation portion that estimates the mold-opening force based on the three-dimensional shape data, wherein:   the controller is configured to control the mold-opening speed of the moving plate such that the mold-opening force that is estimated by the estimation portion is less than the attractive force.   
     
     
         6 . The injection molding machine according to  claim 1 , further comprising an ejector pin drive mechanism that drives an ejector pin for pushing out a product from the moving plate, wherein:
 the separation force is an ejector pin reactive force that is generated in the moving plate when the ejector pin is operated, and   the controller controls the ejector pin drive mechanism such that the ejector pin reactive force is less than the attractive force.   
     
     
         7 . The injection molding machine according to  claim 6 , wherein the controller is configured to control a speed of the ejector pin. 
     
     
         8 . The injection molding machine according to  claim 1 , further comprising:
 a clamping mechanism that drives the moving plate; and   an ejector pin drive mechanism that drives an ejector pin for pushing out a product from the moving plate, wherein:   the separation force is sum of a mold-opening force that is generated in the moving plate in a mold-opening step and an ejector pin reactive force that is generated in the moving plate when the ejector pin is operated, and   the controller is configured to control the clamping mechanism and the ejector pin drive mechanism such that the sum is less than the attractive force.   
     
     
         9 . The injection molding machine according to  claim 1 , further comprising:
 an injection nozzle for supplying material to be injected into a cavity that is formed by the moving plate and the fixed plate, and   a nozzle touch mechanism that drives the injection nozzle, wherein:   the separation force is a nozzle contact force that is generated in the fixed plate by the injection nozzle, and   the controller is configured to control the nozzle touch mechanism such that the nozzle contact force is less than the attractive force.   
     
     
         10 . The injection molding machine according to  claim 1 , further comprising:
 a clamping mechanism that drives the moving plate;   an injection nozzle for supplying material to be injected into a cavity that is formed by the moving plate and the fixed plate, and   a nozzle touch mechanism that drives the injection nozzle, wherein:   the separation force is sum of a mold-opening force that is generated in the fixed plate in a mold-opening step and a nozzle contact force that is generated in the fixed plate by the injection nozzle, and   the controller is configured to control the clamping mechanism and the nozzle touch mechanism such that the sum is less than the attractive force.   
     
     
         11 . The injection molding machine according to  claim 1 , wherein:
 the controller is configured to classify the attractive force into a first class in which control of the separation force to reduce the separation force to less than the attractive force is not required, a second class in which the control is required, or a third class in which the control is impossible, and   the controller is configured to control the separation force such that the separation force is less than the attractive force when the controller judges that the control is required.   
     
     
         12 . The injection molding machine according to  claim 11 , wherein when the controller judges that the control is required, the controller outputs information that indicates that the separation force is to be controlled. 
     
     
         13 . The injection molding machine according to  claim 11 , wherein the controller is configured to output an alarm when the controller judges that the control is impossible. 
     
     
         14 . The injection molding machine according to  claim 1 , wherein:
 the clamp includes magnet blocks each generating magnetic flux that attracts the fixed plate or the moving plate,   the injection molding machine further comprises measurement devices each detecting the magnetic flux for a respective magnet block, and   the controller is configured to calculate the attractive force based on the magnetic flux that is measured by the measurement devices.   
     
     
         15 . A method of operating an injection molding machine, wherein:
 the injection molding machine comprises a clamp that generates an electromagnetic force and a controller, and   the clamp secures a moving plate or a fixed plate to the clamp using an attractive force that is produced by the electromagnetic force,   the method comprises the step of using the controller to control a separation force that acts on the moving plate or the fixed plate such that the separation force is less than the attractive force in a molding process from start of a first operation to release a closed-mold state to completion of a second operation to form a next closed-mold state.